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areaAverage pressure along streamwise direction

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Old   December 16, 2015, 17:43
Default areaAverage pressure along streamwise direction
  #1
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SM
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I want to compute pressure drop across a planar diffuser (2-D) using RANS with simpleFOAM.

I would like to get area averaged pressure
Code:
(sum(Ai*pi)/Sum(Ai))
all along my streamwise (X) direction.

For instance to get area averaged pressure at one particular section
I put in controlDict the following-
Code:
up_plane
{
    type            faceSource;
    functionObjectLibs ("libfieldFunctionObjects.so");
    enabled         true;
    outputControl   timeStep;
    log             true;
    valueOutput     false;// Output field values as well
    source          sampledSurface;   

    sampledSurfaceDict
    {
        type            plane;    // always triangulated
        basePoint       (0.6 0 0);
        normalVector    (1 0 0);
    }
    operation       areaAverage;
    fields
    (
        p
        U
    );
}
But how can I get area averaged p across all along streamwise direction without writing as many files as nodes?
I want data in a single file like
Code:
 x areaAverage(p)


Or is there a way to use sampleDict / pressureTools ?
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Old   March 28, 2016, 16:13
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Bruno Santos
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Greetings canopus,

I've had this post of yours on my to-do list for some time now and I've finally managed to take a look into this.

And I have to say that I'm very confused with your question. I tested just now in the tutorial case "incompressible/icoFoam/cavity" the following entry in "system/controlDict":
Code:
functions
{
    up_plane
    {
        type            faceSource;
        functionObjectLibs ("libfieldFunctionObjects.so");
        enabled         true;
        outputControl   timeStep;
        log             true;
        valueOutput     false;// Output field values as well
        source          sampledSurface;
        sourceName      cookie;

        sampledSurfaceDict
        {
            type            plane;    // always triangulated
            basePoint       (0.05 0 0);
            normalVector    (1 0 0);
        }
        operation       areaAverage;
        fields
        (
            p
            U
        );
    }
}
And after running icoFoam, I got the file "postProcessing/up_plane/0/faceSource.dat" which has something like this:
Code:
#   Source : sampledSurface cookie
#   Faces  : 40
#   Area   : 1.000000e-03
#        Time   areaAverage(p)  areaAverage(U)
5.000000e-03    7.284116e-01    (1.161758e-05 -2.866114e-03 0.000000e+00)
1.000000e-02    1.397881e-02    (-7.844885e-06 -4.445986e-03 0.000000e+00)
1.500000e-02    1.426849e-01    (-1.312083e-05 -5.276828e-03 0.000000e+00)
2.000000e-02    3.357030e-02    (-1.681121e-05 -5.723470e-03 0.000000e+00)
2.500000e-02    3.938627e-02    (-1.845171e-05 -6.021526e-03 0.000000e+00)
3.000000e-02    2.860943e-02    (-1.961279e-05 -6.265176e-03 0.000000e+00)
3.500000e-02    1.667961e-02    (-2.065645e-05 -6.466568e-03 0.000000e+00)
4.000000e-02    3.061324e-02    (-2.121525e-05 -6.647684e-03 0.000000e+00)
4.500000e-02    1.743975e-02    (-2.162312e-05 -6.811977e-03 0.000000e+00)
5.000000e-02    1.584760e-02    (-2.158444e-05 -6.955973e-03 0.000000e+00)
5.500000e-02    1.482289e-02    (-2.202660e-05 -7.083342e-03 0.000000e+00)
6.000000e-02    1.418260e-02    (-2.213669e-05 -7.194694e-03 0.000000e+00)
6.500000e-02    1.309184e-02    (-2.220456e-05 -7.291144e-03 0.000000e+00)
7.000000e-02    1.354508e-02    (-2.222582e-05 -7.373679e-03 0.000000e+00)
and it continues down to Time = 0.5. Each line is for a specific time step.

From what I can figure out, this does what you asked for.

Best regards,
Bruno
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